Field
The present disclosure relates to an organic light emitting display device including different types of thin film transistors disposed on a single substrate.
Description of the Related Art
Recently, with advances in display technology, various display devices with excellent performance, thinner characteristics, more lightweight, and lower power consumption have been developed.
Specific examples of display devices include a liquid crystal display (LCD) device, an organic light emitting display (OLED) device, an electro phoretic display (EPD) device, and an electro-wetting display (EWD) device, and the like. Particularly, the OLED device, which is a display device with self-emitting characteristics, has excellent characteristics in terms of viewing angle, contrast ratio, response speed, power consumption, etc., as compared with the LCD device.
The OLED device includes a display area where an organic light emitting diode used for displaying an image and a pixel circuit for driving the organic light emitting diode are disposed. Also, the OLED device includes a non-display area which is adjacent to the display area and in which a driving circuit is disposed. Particularly, a plurality of thin film transistors exist in the pixel circuit and in the driving circuit so as to drive the organic light emitting diodes in a plurality of pixels.
The thin film transistors (TFTs) can be classified by the material of its active layer. Particularly, low temperature poly-silicon (LTPS) TFTs and oxide semiconductor TFTs are commonly used. However, in related art OLED devices, only LTPS TFTs or only oxide semiconductor TFTs are used on a single substrate in pixel circuits and driving circuits. However, having only LTPS TFTs or only oxide semiconductor TFTs in the pixel circuit and the driving circuit result in certain limitations in performance of the OLED device. Accordingly, there has been a need to employ different types of thin film transistors in a single OLED device.